Scaffold tube coupler

ABSTRACT

A coupler for connecting a pair of round scaffold tubes, embodying hinged tube clamping jaws having limited opening movement but exceeding 90* such as to allow lateral initial positioning of the scaffold tube passed the clamping bolt.

United States Patent [19] Lowe [45] May 14,1974

[ SCAFFOLD TUBE COUPLER [75] Inventor: Jack Graham Lowe, Belbroughton,

England [73] Assignee: Burton Delingpole & Company Limited, Warley, Worcester, England 22 Filed: July 28, 1972 [2]] Appl. No.: 276,011

[30] Foreign Application Priority Data July 30, 1971 Great Britain 35850/71 52 US. Cl. 403/385 51 Int. Cl. F16b 1/00 [58] Field of Search.....v 287/54 B; 403/188, 385, 403/391 [56] References Cited UNITED STATES PATENTS 3,512,814 5/1970 Lowe 287/54 B FOREIGN PATENTS OR APPLICATIONS 447,865 5/1936 Great Britain 287/54 B Primary ExaminerAndrew V. Kundrat Attorney, Agent, or FirmA. Yates Dowell, Jr.

[57] ABSTRACT A coupler for connecting a pair of round scaffold tubes, embodying hinged tube clamping jaws having limited opening movement but exceeding 90 such as to allow lateral initial positioning of the scaffold tube passed the clamping bolt.

3 Claims, 2 Drawing Figures 1 SCAFFOLD TUBE COUPLER I BACKGROUND OF THE INVENTION 1. Field of the Invention v This invention relates to couplers for connecting two round scaffold tubes together and of the kind, herein called the. kind specified, which comprises a central body formed as a metal drop forging having on each of two opposite sides thereof a tube receiving seating, the seatings being so relatively disposed that the two tubes are connected together in mutually perpendicular relationship, the body at each of two opposite sides thereof adjacent each seating being provided with a pair of binge lugs formed integrally with the central body during the drop forging operation,.so that each of the four lugs embody substantially the same mass of metal, one of the two lugs of each pair having hinged thereto one end of one of two tube securing jaws each formed to provide a tube receiving recess, and the other of the two lugs of each pair having hinged thereto a clamping bolt arranged for detachable clamping engagement with the other and free end of one of the two jaws, each clamping bolt being adapted to hinge under its own weight towards its associated jaw'when the latter is at a horizontal level which is below that of the bolt, means being provided for limiting such hinging movement of each clamping bolt, the two lugs of each pair being disposed on diametrically opposite sides of their respective seatings, with the one end of each jaw connected to the jaw hinging lug being forked, with each jaw hinging lug extending between the two arms of the fork and being engageable at itsfree end with the jaw at the base of the fork so as to provide a stop to limit the opening pivotal movement of the jaw. I

2. Description of the Prior Art Hitherto in couplers of the kind specified, the opening pivotal movement of each jaw has been limited by the said stop to substantially 90. Thus the coupler can be clamped by one of two jaws to a vertically disposed tube with the other jaw extending from the lower side of its associated body seating in a horizontal position in which it is so retained by the said stop, that the recess of said horizontal jaw can receive and support a horizontal tube which is to be connected by the coupler to said vertical tube. Such an arrangement permits of the scaffolding erector so supporting a horizontal tube from the open horizontal jaws of two couplers each already clamped to spaced apart vertical tubes, while the horizontal tube is adjusted in the direction of its length into the required position for connecting it to the two vertical tubes.

To enable the horizontal tube to be so supported from the horizontally extending jaw of each coupler, it is most desirable that it can be displaced transversely of its length into position. Hitherto in couplers of the kind specified. difficulties have been encountered in so doing in practice, because as the horizontal jaw referred to cannot be pivoted through more than substantially 90 away from its associated body seating, the free end portion of the clamping bolt which is required to have clamping engagement with said horizontal jaw is liable, despite the means limiting its pivotal movement abovementioned, to be so close to the free end of the at present horizontal jaw as to foul that side of the horizontal tube which is nearest to the vertical tube when such horizontal tube is displaced in a direction SUMMARY OF THE INVENTION According to this invention, the stop forming free end of each jaw hinging lug is chamfered at a position and to an extent such as to allow the associated jawto swing outwardly away. from the associated body seating through an angle-sufiiciently greater than as to per-' mit of the horizontal tube being engaged with the said open jaw by displacing the tube transversely of its length without manually grasping and manipulating the adjacent clamping bolt in so doing, said angular opening movement of each jaw being so limited by the engagement between the associated stop forming lug and the open jaw, that the horizontal tube is still received in and supported by the recess of said open jaw, and each jaw hinging lug adjacent its junction with the central body having its cross section increased and thus strengthened against bending by a mass of metal substantially equal to that saved by the said chamfering, so as to maintain substantially the same mass of metal in each of-the four lugs of the body.

This last'mentioned feature facilitates the drop forging of each body with the maximum economy of metal and enables two such bodies to be simultaneously drop forged on a forging press of a size such as to be capable of forging only one body at a time in the case where there is substantial difference in the mass of metal in each of the four lugs.

Preferably the extent of chamfering of each stop forming lug is such that the spacing between the free end of the fully open jaw and the free end of the associated bolt when in the free position is less than the peripheral diameter of the round horizontal tube, but large enough to allow the convexedly curved upward directed periphery of the round horizontal tube by its engagement with the free end of the bolt to urge the latter upwardly about its hinge as the horizontal tube is displaced transversely of its length towards the coupler body. Such an arrangement avoids providing such a large opening movement of the jaw as to render it less effective in supporting the horizontal tube before this is finally clamped into position. Thus the'opening angular movement of each jaw need be no more than about l00 to 1 10 as opposed to the hitherto customary substantially 90.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to the accompanying drawings wherein:

FIG. 1 is a side elevation partly in section of one form of hitherto used coupler of the kind specified.

FIG. 2 is a view similar to FIG. 1 but depicting the coupler of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring firstly to FIG. 2 of the drawings, the coupling there illustrated is intended for use in connecting two scaffold tubes together, in fixed mutually perpendicular relationship and comprises a central body 9 embodying in each of its two sides two mutually perpendicular concave seatings 10, 11 so as to be adapted to extend between the two scaffold tubes. In this view, as also with FIG. 1, only the one concave seating 11 and its associated lugs are seen fully in side elevation but it will be readily understood by those familiar with this kind of cover that the other concave seating and its associated lugs have the same formation as those described with reference to the concave seating 11.

The body at the periphery thereof has integrally formed therewith, two mutually transverse pairs of lugs 12, 13, and 14, (the other one not being seen), with the two lugs in each pair disposed at diametrically opposite sides of the central body 9. One of the lugs l2, 14, in each pair and which constitute jaw hinging lugs is devoid of oppositely extending flanges so as to be of substantially rectangular form in cross section, and the other lug 13, 15 of each pair is formed in one side with an open-mouthed recess 16 of shallow depth e.g. about 5 mms. deep, and of part-circular form in cross-section so as to provide a hinge bearing for a cylindrical head 17 of a T-shape clamping bolt 18, which head 17 has a diameter substantially twice the depth of the recess 16 so that only substantially half of the bolt head is received within the recess 16. The associated lug 13, is thus made of the minimum depth consistent with the provision of this recess 16 of the above shallow depth. Each recess 16 is elongated in a direction parallel to the hinge axis ofthe diametrically opposite jaw hinging lug 12, 14, so as to accommodate the bolt head 17.

Preferably, as shown in FIG. 2, the bolt head receiving recess 16 of each of the bolt hinging lugs 13, 15 has its two opposite elongated sides 16a relatively inclined towards one another in a direction inwardly of the mouth 16b of the recess. Also, the mouth 16b of each recess 16 has a width which is substantially equal to the length ofthe elongated bolt head 17. The relative inclination of the two recess sides 16a in a direction inwardly of the recess mouth 16b is such, that with the bolt partially withdrawn from its associated recess 16 with its stem 18a extending substantially vertically in a downward direction from the head 17 and with the latter disposed substantially at right angles to the length of the elongated recess 16, if the coupler is now manually shaken, the resultant reaction between at least one ofsaid two inclined recessed sides 16a and the adjacent end of the bolt head causes the latter to turn about the axis of stem 18a so as to allow the bolt head, under the weight of the bolt, to drop downwardly into its correct position within the recess 16 as depicted in FIG. 2.

Thus the bolt head can readily be displaced from a position in which it fouls and thus interferes with the positioning of the adjacent scaffold tube.

Despite the provision of the foregoing feature of the co-pending application, each bolt hinging lug 13, embodies substantially the same mass of metal as that embodied in the jaw hinging lugs l2, l4, i.e. the mass of metal in each of the two diametrically opposed lugs in each pair of lugs is substantially the same.

As appears from the drawing, the periphery of the body 9 is devoid of projecting corners at positions intermediate the positions of the four lugs, three of which are seen at l2, l3, 14. Thus the body 9 is not of the hitherto rectangular configuration peripherally involving intermediate the said lugs, projecting corners which are wasteful in metal.

Each recessed lug 13, is formed with an elongated hole through which the stem 18a of the respective clamping bolt 18 passes. The free end portion of the clamping bolt carries a nut 20 for engaging with the free end portion 21 of one of a pair of clamping jaws 22, 23, the other end portion 24 of each of which jaws is hinged by pin 25, one to each of the substantially rectangular section lugs 12, 14. Thus each pin 25 provides a hinge bearing for the corresponding jaw. Each jaw 22, 23 has a concavedly curved tube engaging recess 22a, 23a respectively.

As shown in FIG. 2, the major width of each elongated hole in the recess 16, i.e. in a direction transverse to the length of the bolt stem 18a, is such as to permit of the bolt being pivoted into a fully disengaged position shown at 18' in FIG. 2 in which the bolt is well clear of the free end 21 of the associated jaw when the latter is still in clamping position relative to the scaffold tube facilitating the removal of the associated scaffold tube.

The width of each hole is however such as to prevent the bolt 18 under its own weight pivoting downwardly beyond the free position depicted in full outline in FIG. 2 for the reason explained later herein.

The central body 9 is formed integrally during the forging thereof, with two pairs of lug reinforcing portions two of which are seen at 120, 13a, each extending from the central body 9 adjacent the two pairs of lugs three of which are seen at l2, l3, 14, respectively and in the direction in which the respective adjacent lug extends from the central body.

The construction as so far described permits of two bodies 9 each with their associated four lugs being drop forged simultaneously from a single length of forging steel bar, by a single drop forging press of a size normally used only for forging at one time only one body of a coupler of the kind specified.

This is done by taking a length of round forging steel bar which is subjected to the step of a local preliminary swaging operation so as to form the bar locally with flattened rectangular section portions thereby elongating the bar over a length corresponding to that of each of the rectangular portions.

The bar is then severed into separate portions, so as to embody two cylindrical parts connected by the aforementioned rectangular portion which in the preliminary swaging operation is formed to a length great enough to provide therein sufficient metal to form two of said bolt hinging lugs each associated with a respective one of the two central bodies 9. This severed length of bar is then placed in a known form of forging press, or a drop forging hammer, but provided with two pairs of forging dies arranged and shaped, to forge at one and the same time, two connected together central bodies 9, with one of the two hinging lug forming parts of the two forging dies of one pair being aligned with and adjacent to a corresponding part of the other pair of dies.

Thus when the so formed length of bar is placed between the two dies of both pairs of forging dies of the press or hammer, with the major axis of cross section of the flattened portion perpendicularly transverse to the direction of relative movement of the forging dies, the bar is forged by a succession of blows, of the press or hammer to the configuration substantially that of two of the central bodies 9.

Reference is now made to FIG. I which depicts one form of hitherto used coupler of the kind specified. In

this Figure, the same references are used where applicable as in the construction according to this invention shown in FIG. 2. In this previously known construction, the above mentioned hinged end portion 24 of each jaw 22, 23, is forked so that the arms 26 of the fork extend on opposite sides of the corresponding lug 12, I4, and the free end 27 of each of these lugs l2, 14 is adapted as shown in FIG. 1 to engage with the metal of the jaw at a position 28 between the inner ends of the two arms 26 to provide a stop to limit the opening movement of each jaw 22, 23. This latter feature is of practical importance in that with the jaw 22 of one half of the coupling secured first, as is customary, to a vertically extending, i.e. upright, tube 29, forming one of the two tubes to be connected, then as shown in FIG. 1, the jaw 23 of the other half of the coupling can be supported in a horizontal position to provide a rest for a horizontal tube 30, namely the other tribe to be connected, before this is finally clamped by such jaw 23 in position.

The configuration of the free end 27 of each of the jaw hinging lugs I2, I4, is however such that as shown in FIG. I each jaw, i.e., the depicted open jaw 23 can only be swung downwardly through an angular distance of substantially 90 from its tube clamping position. In this horizontal tube supporting position the minimum distance between the free end portion 21 ofjaw 23 and the free end of the associated bolt 18 when in the full outline free position is so much less than the outside diameter of the tube 30, that the bolt extends substantially radially in relation to the centre of the tube 30 when an attempt is made to advance the tube transversely of its length into a position for being received within seating 230. The foregoing is illustrated by the position 30' then occupied by the tube 30 the side of which that is nearest to the vertical tube and coupler body is in abutting engagement with the end face of either the bolt or nut thereon.

Thus the tube 30 can be advanced into a position for being supported by open jaw 23 if bolt 18 is grasped by one hand of the operator and swung upwardly from the depicted full outline position.

The foregoing cannot satisfactorily be taken care of by reducing the major width of each abovementioned elongated hole in the recess 16 so as to prevent the clamping bolt 18 under its own weight swinging downwardly as far as the position depicted in FIG. 1, which is the same as the FIG. 2 position, as that may prevent the bolt from being effectively brought into clamping engagement with the associated jaw.

The above difficulty is taken care of by the embodiment of the present invention shown in FIG. 2 from which it will be seen that as in the previously used construction of FIG. I, the hinged end portion 24 of each jaw 22, 23 is forked so that the arms 26 of the fork extend on opposite sides of the corresponding lug l2, l4

and the free end 27 of each of these lugs l2, 14 is two arms 26 to provide astop to limit the opening movement of each jaw 22, 23.

With the embodiment of the present invention shown in FIG. 2, the above described stop forming free end 27 of each of the two jaw hinging lugs l2, 14 is chamfered at 27a as compared with the configuration of the free end 27 of each of these two lugs in the previously used coupler depicted in FIG. 1. The extent of the chamfering is such as to permit of each jaw, i.e. jaw 23 being swung away from the associated body seating until the chamfered free end 270 engages jaw part 28 and so that the jaw has now been swung through a distance such that a line L L passing through the axis of pivoting of the jaw 23 and the centre of the free end 21 isinclined downwardly at substantially 10 to 15 to the horizontal in a direction towards the end 21 of the jaw, instead of such line L L being substantially horizontal as in the previously used arrangement depicted in FIG. 1.

Thus with the jaw 23 in the tube supporting position depicted in FIG. 2, the minimum distance between the free end portion 21 of jaw 23 and the free end of the associated bolt 18 when in the free position shown in full outline in the drawings, although still less than the outside diameter of the tube 30, is large enough to allow the convexedly curved upwardly directed periphery of the round horizontal tube by its engagement with the free end of the bolt to urge the latter upwardly about its hinge as the horizontal tube is displaced transversely of its length towards the coupler body. The foregoing is illustrated in FIG. 2 by the position 30' occupied by the tube 30 when advanced in a direction transversely of its length between the free end of the bolt and the free end portion 21 of the jaw 23 in the supporting position.

The extent to which the free end 27 of each of the jaw hinging lugs is chamfered, as shown in FIG. 2, as compared with the previously used arrangement of FIG. 1 is, however, such that with the jaw 23 in the supporting position, the free end 21 thereof is still at a horizontal level higher than the bottom of the jaw recess 23a, so that with the tube 30 supported as shown in FIG. 2, there is no risk of the tube 30 rolling under its weight over the free end portion 21 of its supporting jaw 23.

To ensure that as already described two bodies 9 can readily be drop forged at one and the same time on the one forging press and with the maximum economy of metal, i.e. forging steel, the mass of metal in each jaw hinging lug l2, 14 is maintained the same as that in each bolt hinging lug 13, despite the removal of metal by the abovementioned chamfering 270. This is done by increasing the thickness of each of the lugs l2, 14 in a direction perpendicular to the axis ofjaw hinge pin 25 at a position between the latter and the body 9.

Thus the side of each lug 12,,14 directed away from the associated seating 11, 10 respectively, is rectilinear instead of being concave as in the previously used construction of FIG. 1. As a result, as compared with this previously known construction, each lug l2, 14 is strengthened at a position between the pin 25 and the junction of the lug with the central body, which is an important advantage in that the jaw hinging lugs are subjected to a very high tensile load when the clamping bolts are tightened. Thus the aforementioned lug reinforcing portions 12a are made more effective in strenghening their respective associated lugs l2, l4.

If desired, the free end portion 21 of each jaw, which is forked to receive the stem 18a of the bolt, may have a width slightly greater than that of the remainder of the jaw, so as to permit of the two arms of such forked end to be formed with upstanding arcuate shaped flanges which flanges, with the clamping nut 20 tightened, engage with the cylindrical base of the nut at the side thereof furthest from the associated jaw hinge, thus more securely retaining the nut in clamping engagement with the free end 21 of the jaw.

I claim:

1. A coupler for connecting two round scaffold tubes together and of the kind, which comprises a central body formed as a metal drop forging having on each of two opposite sides thereof a tube receiving seating, the seatings being so relatively disposed that the two tubes are connected together in mutually perpendicular relationship, the body at each of two opposite sides thereof adjacent each seating being provided with a pair of hinge lugs formed integrally with the central body during the drop forging operation, so that each of the four lugs embody substantially the same mass of metal, one of the two lugs of each pair having hinged thereto one end of one of two tube securing jaws each formed to provide a tube receiving recess, and the other of the two lugs of each pair having hinged thereto a clamping bolt arranged for detachable clamping engagement with the other and free end of one of the two jaws, each clamping bolt being adapted to hinge under its own weight towards its associated jaw when the latter is at a horizontal level which is below that of the bolt, means being provided for limiting such hinging movement of each clamping bolt, the two lugs of each pair being disposed on diametrically opposite sides of their respective seatings, with the one end of each jaw connected to the jaw hinging lug being forked, with each jaw hinging lug extending between the two arms of the fork and being engageable at its free end with the jaw at the base of the fork so as to provide a stop to limit the opening pivotal movement of the jaw, characterised in that the stop forming free end of each jaw hinging lug is chamfered at a position and to an extent such as to allow the associated jaw to swing outwardly away from the associated body seating through an angle sufiiciently greater than as to permit of the horizontal tube being engaged with the said open jaw by displacing the tube transversely of its length without manually grasping and manipulating the adjacent clamping bolt in so doing, said angular opening movement of each jaw being so limited by the engagement between the associated stop forming lug and the open jaw, that the horizontal tube is still received in and supported by the recess of said open jaw, and each jaw hinging lug adjacent its junction with the central body having its cross section increased in a direction perpendicular to the axis of the jaw hinge pin to provide a rectilinear side directed away from the central body and thus strengthen it against bending by a mass of metal substantially equal to that saved by the said chamfering, and so as to maintain substantially the same mass of metal in each of the four lugs of the body.

2. A coupler according to claim 1, characterized in that the extent of chamfering of each stop forming lug is such that the spacing between the free end of the fully open jaw and the free end of the associated bolt when in the free position is less than the peripheral diameter of the round horizontal tube, but large enough to allow the convexedly curved upwardly directed periphery of the round horizontal tube by its engagement with the free end of the bolt to urge the latter upwardly about its hinge as the horizontal tube is displaced transversely of its length toward the coupler body.

3. A coupler according to claim 1 characterized in that the maximum opening angular movement of each jaw does not exceed a value within the range of to 

1. A coupler for connecting two round scaffold tubes together and of the kind, which comprises a central body formed as a metal drop forging having on each of two opposite sides thereof a tube receiving seating, the seatings being so relatively disposed that the two tubes are connected together in mutually perpendicular relationship, the body at each of two opposite sides thereof adjacent each seating being provided with a pair of hinge lugs formed integrally with the central body during the drop forging operation, so that each of the four lugs embody substantially the same mass of metal, one of the two lugs of each pair having hinged thereto one end of one of two tube securing jaws each formed to provide a tube receiving recess, and the other of the two lugs of each pair having hinged thereto a clamping bolt arranged for detachable clamping engagement with the other and free end of one of the two jaws, each clamping bolt being adapted to hinge under its own weight towards its associated jaw when the latter is at a horizontal level which is below that of the bolt, means being provided for limiting such hinging movement of each clamping bolt, the two lugs of each pair being disposed on diametrically opposite sides of their respective seatings, with the one end of each jaw connected to the jaw hinging lug being forked, with each jaw hinging lug extending between the two arms of the fork and being engageable at its free end with the jaw at the base of the fork so as to provide a stop to limit the opening pivotal movement of the jaw, characterised in that the stop forming free end of each jaw hinging lug is chamfered at a position and to an extent such as to allow the associated jaw to swing outwardly away from the associated body seating through an angle sufficiently greater than 90* as to permit of the horizontal tube being engaged with the said open jaw by displacing the tube transversely of its length without manually grasping and manipulating the adjacent clamping bolt in so doing, said angular opening movement of each jaw being so limited by the engagement between the associated stop forming lug and the open jaw, that the hoRizontal tube is still received in and supported by the recess of said open jaw, and each jaw hinging lug adjacent its junction with the central body having its cross section increased in a direction perpendicular to the axis of the jaw hinge pin to provide a rectilinear side directed away from the central body and thus strengthen it against bending by a mass of metal substantially equal to that saved by the said chamfering, and so as to maintain substantially the same mass of metal in each of the four lugs of the body.
 2. A coupler according to claim 1, characterized in that the extent of chamfering of each stop forming lug is such that the spacing between the free end of the fully open jaw and the free end of the associated bolt when in the free position is less than the peripheral diameter of the round horizontal tube, but large enough to allow the convexedly curved upwardly directed periphery of the round horizontal tube by its engagement with the free end of the bolt to urge the latter upwardly about its hinge as the horizontal tube is displaced transversely of its length toward the coupler body.
 3. A coupler according to claim 1 characterized in that the maximum opening angular movement of each jaw does not exceed a value within the range of 100* to 110*. 